Would you know the tell-tale signs of Chronic Kidney Disease (CKD) in your pet?
Some common signs include: drinking more water, urinating more frequently, losing weight/muscle mass and accidents in the house, amongst others. Kidney disease is defined as a structural or/and functional impairment of the kidney; once considered to be part of the ageing process, CKD is now beginning to affect younger dogs. CKD is an interestingly condition as it is managed nutritionally, with specific veterinarian prescribed foods to help slow progression.
The formulations are usually restricted in phosphorus, sodium, protein, and higher in omega 3. In terms of prevention, we can manipulate some of the nutrients above to support overall kidney health and create less waste in the body, depending on the food choices we make. Take a look at the top tips below and avoid some common mistakes, potentially helping to prevent the early onset of CKD.
Water! Yes, it is a nutrient! We are made of water and our fluid medium allows for millions of processes to take place in the body. The main role of the kidneys is to filter waste products from the blood by producing urine as a means of elimination. In humans, some of the most common dis-eases can be due to dehydration – think headaches, tiredness, even morning sickness, heartburn and high blood pressure, to some extent! Water is vital for vitality and healthy kidneys! Most pets will drink enough water on their own to stay well hydrated, however, if you are feeding a dry food you might like to consider moving to a wet food to increase water intake. Or, if kibble is your best choice, then consider adding some fresh, moisture-rich toppers like lean protein sources, such as turkey thigh or a few vegetables. And when it comes to water, fresh is best. Certainly avoid the dregs of water from metal and plastic bottles when you are out and about, as they can accumulate toxins and bacteria – any step to make water fresher and cleaner will support their kidneys.
Include some calcium eggshell if you are not feeding raw bone. Perhaps the most well known mineral concerned with kidney health is phosphorous; excessive phosphorus levels correlate to increase risk of developing chronic kidney disease. Yet, phosphorus is ubiquitous in foods and a required Essential nutrient – vital for our energy making processes. In many cases, it is a lack of calcium that can exacerbate problems. Calcium binds to phosphorus and too little calcium (over a period of months) can cause calcium to be leeched from the bone to meet requirements (called nutritional secondary hyperparathyroidism), resulting in elevated levels of phosphorous. Clearly, wolves knew to eat both the meat and the bone, as meat is mainly phosphorus with little calcium, and vice versa. Many raw diets contain ground bone and therefore you do not need to supplement with eggshell. In comparison, home-cooked diets, without bone, the estimated calcium value would be around 5%-10% of the RDA (with small amounts coming from vegetables and grain), and therefore eggshell is recommended. You can buy eggshell powder on Amazon or make your own. Too much calcium can be equally problematic so it is important to work out how much calcium eggshell is required for your dog; you can find out how to work out requirements in my Cooking Handbook on the website.
As a carbohydrate choice, white rice is often recommended in late stages of CKD, as a way to further restrict phosphorus levels in the diet, however, in terms of prevention I would always go with moderate feeding of organic whole-grains, such as brown rice. While there is more phosphorus in brown rice it is far more nutritious. When rice is milled and polished it leaves only the endosperm, which is mainly carbohydrate; the lovely fibre, antioxidants, oil, minerals and vitamins that would be in the full grain are removed in the milling process, and nutrients are added back in artificially! Given that the plant form of phosphorus, called phyrate, is less readily absorbed, I would always prefer to provide nutrients over empty calories, unless it was absolutely necessary. Buckwheat is a nutritious, alternative choice with a slightly lower phosphorus content than brown rice; plus it is always a good idea to rotate and feed a variety of foods to provide an array of nutrients!
Bones, dairy, organ meat and egg yolks contain the highest levels of phosphorus. It is not about removing these foods from your dog’s diet, as they are vital in a canine diet to supply calcium, fat soluble vitamins and choline/biotin, respectively. It is about moderate feeding, rather than relying on them as a main protein. Phosphorus per 100g, is lowest in lamb, followed by beef, chicken, rabbit and salmon. Green tripe is an excellent addition to your dog’s diet because it is low in phosphorus and dogs usually enjoy it. Note, the green or unwashed tripe is much better as it contains beneficial gut bacteria.
Some nutritionists like to feed only the white of an egg when suffering from CKD, the whites having lower phosphorus levels, compared to the yolk, but again, a balanced argument. In terms of prevention I would always feed the whole egg. The yolk is more nutritionally dense, and eggs have a high biological value (less waste produced compared to many proteins), as well as being a a great source of biotin for healthy skin, immunity and fat digestion.
Phosphorus is not the only consideration however. Protein restriction is often recommended in the management of CDK but currently a big debate. Protein restriction can actually result in diminished immune function and lead to muscle loss, and some older dogs actually need more protein. Is there a way round this? Well, some proteins leave less waste behind than others, so although phosphorus is present, the kidneys have less work to do. Foods that have a high biological value mean the majority of the components can be digested – whole eggs being complete (all of it can be digested) followed by fish, lamb, beef, are good examples. Lower-quality foods such as corn and wheat, which are best avoided as they have fewer Essential amino-acids and excesses must be passed out of the body. Proteins cooked at lower temperatures are also more easily digested than extruded forms, such as kibble.
In general, try to choose lower sodium food choices. Sodium and potassium are needed to maintain correct blood pressure and excesses are excreted by the kidneys. When it comes to sodium, reducing levels has been shown to decrease blood pressure in human, while there is little evidence of sodium restriction for dogs, and a vital nutrient, it does make sense to avoid excessive intake. Common culprits are commercial human foods, which usually contain high levels of additional sodium; for example, cured meats, broths, and canned foods like fish and vegetables. Using fresh food is always the best way but if you must use canned items, rinse the food well to remove some of the additional sodium and unnecessary sugars.
Pumpkin, Squash or Sweet Potato are nice additions as they contain good amounts of potassium, beneficial for kidney health (and often harder to meet requirements, in comparison to sodium). Green vegetables contain folate which is needed to make the master antioxidant, glutathione. I love the advantages of healthy antioxidants, which protect the body and cells from damage; cauliflower is a versatile vegetable too. A slice of apple can be a healthful snack that contains an important fibre called pectin; pectin may help reduce some risk factors for kidney damage so why not let
your dog enjoy an occasional healthy, hydrating snack?
Cabbage and red peppers contain small amounts of Coenzyme Q10 (CoQ10), an essential compound which helps to digest fat and may help to protect the kidneys. Plasma concentrations of CoQ10 were found to be depressed in patients with CKD, so it makes sense to include some foods which contain this valuable compound, especially as production of CoQ10 depreciates with age!
COQ10 is a fat soluble compound and therefore, the highest levels are actually found in oily or fatty foods. Mackerel has a few other benefits too. It is classed as a ‘low mercury’ fish as well as a good source of vitamin D and omega 3. One role of the kidney is to change Calcitriol (the precursor of active vitamin D) into the usable form, D3. Dogs with CKD were shown to have lower levels and so a little vitamin D boost could prove beneficial and another great reason to include a little oily fish.
Furthermore, there are wide reports that omega 3 can slow the decline of CKD, by reducing inflammation and in particular, reducing glomerular capillary pressure. In simple terms omega 3 (mainly found in oily fish) completes with our pro-inflammatory omega 6s -(mainly found in meats); a little like calcium and phosphorus, it is the balance between them which is important. Most canine diets are excessively high in omega 6 and a little additional oily fish can be a good way to balance. I think I have mentioned this in a previous blog, but if you increase oily fish you should also increase vitamin E to reduce oxidation – once again, you can read more in my Cooking Handbook.
Functional foods are foods that have a nutritional function or medicinal qualities. Cordyceps cicadae, is a mushroom – that lives off the larvae of Cicada flammata Dist. There is some evidence that cordyceps mushrooms have beneficial effects in reducing the progression of end-stage kidney disease – most likely because of their antioxidant properties. Schisandra berries (Schisandra chinensis), a member of Magnoliaceae family were also found protective in cases of nephrotoxicity; containing flavonoids and polyphenols which help in the detoxification pathways. Both Cordyceps and Schisandara berries have been used in Chinese medicine for thousands of years and considered safe. I give a pinch now and again to my dogs when I am having some myself. I would never recommend feeding a functional food routinely as we still need more research on the long-term effects, but the odd pinch could be a consideration for additional antioxidants; it would also be prudent to speak with your vet, especially if your dog is taking regular medication as interactions are always possible.
D’Alessandro, C., Piccoli, G. B., & Cupisti, A. (2015). The “phosphorus pyramid”: a visual tool for dietary phosphate management in dialysis and CKD patients. BMC nephrology, 16, 9. https://doi.org/10.1186/1471-2369-16-9
A. Galler, J.L. Tran, S. Krammer-Lukas, U. Höller, J.G. Thalhammer, J. Zentek, M. Willmann,Blood vitamin levels in dogs with chronic kidney disease,The Veterinary Journal,Volume 192, Issue 2,2012,Pages 226-231https://doi.org/10.1016/j.tvjl.2011.06.026.
Advances in Nutrition: An International Review Journal (2014), 5, 104; The American Journal of Clinical Nutrition, (2013), 98, 6; Journal of Feline Medicine and Surgery, (2017);
Xu, Y., Liu, J., Han, E., Wang, Y., & Gao, J. (2019). Efficacy of coenzyme Q10 in patients with chronic kidney disease: protocol for a systematic review. BMJ open, 9(5), e029053. https://doi.org/10.1136/bmjopen-2019-029053
Zhang HW, Lin ZX, Tung YS, Kwan TH, Mok CK, Leung C, Chan LS. Cordyceps sinensis (a traditional Chinese medicine) for treating chronic kidney disease. Cochrane Database of Systematic Reviews 2014, Issue 12. DOI:10.1002/14651858.CD008353.pub2. Accessed 15 February 2022.
Hairston, N. Phosphorus: time for us to oust bad spelling. Nature 426, 119 (2003). https://doi.org/10.1038/426119c